We did the RS4K Chem. and Bio. last year, and just completed the Physics. As mentioned above we enjoyed all 3, but are taking a break for a while and probably going to use Harcourt (through Kolbe)
for a while.I just ordered the texts, so I will have to see if we are going to like them first. We may go back and do more RS4K later. Next year I will be doing the pre-level 1 Chem. with my youngest.